I creep around being useful to the cook (6)
I believe the answer is:
recipe
'useful to the cook' is the definition.
(a recipe is useful to a cook)
'i creep around' is the wordplay.
'around' indicates an anagram.
'i'+'creep'='icreep'
'icreep' anagrammed gives 'RECIPE'.
'being' is the link.
(Other definitions for recipe that I've seen before include "Cook's formula" , "List of ingredients" , "Directions for preparing food, etc" , "Directions for cooking the turkey e.g." , "Kitchen directions" .)